1. Field
Apparatuses consistent with the following description relate to an input device, and more particularly, to an input sensing device and a touch panel including the same.
2. Description of the Related Art
A touch panel is one example of a kind of user input device used to determine whether a user generates an input and the position of the user's input signal by sensing the user's contact thereon. A user may input data or signals to a touch panel by contacting or pressing a surface of the touch panel with a finger, a stylus pen or the like. The touch panel may be used as a touch pad functioning like a mouse in a laptop computer or a netbook, etc., or as an input switch of an electronic device. Also, the touch panel may be used in association with a display. A touch panel which is mounted on the screen of a display device, such as a liquid crystal display (LCD), a plasma display panel (PDP), a cathode ray tube (CRT) and the like, is generally called a “touch screen”. A touch panel may be integrated with a display device to configure the screen of the display device or may be attached additionally on the screen of the display device.
In certain situations, a touch panel may be substituted for a user input device such as a keyboard, trackball, or mouse, and also may allow for simple manipulations. Moreover, the touch panel can provide users with various types of buttons according to the types of applications to be executed or stages of the executed application. Accordingly, a touch panel, and more specifically, a touch screen has been widely used as an input device for electronic equipment, such as a mobile phone, a personal digital assistant (PDA), a portable media player (PMP), a digital camera, a portable games, a Moving Picture Experts Group Layer-3(MP3) player, etc., as well as an automated teller machine (ATM), an information trader, a ticket vending machine, etc.
A touch panel can be classified into a resistive type, a capacitive type, an ultrasonic type, an infrared type, etc., according to methods of sensing user's inputs. Since the individual touch panel types have their unique merits and demerits, an appropriate method has been selected and used according to the types of applications, the use purpose of the touch panel, etc. A related art touch panel has a limitation in recognizing multiple touches, but recently, a capacitive type touch panel allowing multi-touch recognition has been introduced.
Capacitive type touch panels may be classified into a self-capacitive type and a mutual-capacitive type. The self-capacitive type provides a single electrode, for example, a sensor electrode, whereas the mutual-capacitive type provides a pair of electrodes facing each other with dielectric therebetween, that is, a capacitance node. The self-capacitive type and the mutual-capacitive type use different basic principles to determine whether there is an input. For example, a self-capacitive type touch panel may determine whether there is an input, based on differences in charge amount transferred through a sensor electrode caused by a touch. Meanwhile, a mutual-capacitive type touch panel may determine whether there is an input, based on changes in node capacitance caused by occurrence of a touch.
U.S. Patent Application Publication No. 2006/0097991 discloses an example of an input sensing circuit for sensing changes in node capacitance in a mutual-capacitive type touch panel. The input sensing circuit uses changes in capacitance between upper and lower electrodes due to differences in leaking charge amount caused by a touch. More specifically, a sensing signal is applied through a driving line so that the magnitude of the signal transferred to a sensing line changes due to a change in node capacitance, and the input sensing circuit amplifies the magnitude of the signal using a charge amplifier, etc. and then performs analog-to-digital conversion, thereby determining whether there is a touch. The disclosure of U.S. Patent Application Publication No. 2006/0097991 is herein incorporated by reference.